The subject matter disclosed herein relates to a system for operating a steam system, and in particular relates to a system for predicting steam system properties and the locations of undesired conditions.
In large metropolitan areas, it is not uncommon for a central heating plant to be used to generate heat for multiple facilities in the surrounding area. This heating system is sometimes referred to as district heating or teleheating. The steam is transported via insulated pipes to subscribing buildings, which purchase the steam from the steam utility. Similar to an electric meter, a steam meter measures the amount of steam used by a particular building and the building owner is charged on a periodic basis.
The transfer of the steam from the central heating plant often results in the routing of steam pipes under streets and other areas. The steam pipes are insulated, and often enclosed within conduits to protect the insulation and steam pipes from the surrounding environment and to allow for thermal growth and movement of the pipes. During the normal course of transfer, some portion of the steam will condense back into liquid form. The condensed water is typically drained to the lowest point in the system where a device, such as a steam trap is installed. The steam trap is arranged to open when condensate is present and close in the presence of steam. The condensate is removed from the system to prevent a phenomena known as “water hammering” from occurring. Water hammering occurs if sub-cooled condensate backs up into the steam section of the system.
There are two types of water hammering: 1) slug type; and, 2) steam bubble collapse. In slug type water hammering, the high velocity steam propels a “slug” of condensate into a fitting such as an elbow that causes a change in the direction of the flow. The impact of the slug against the fitting creates a loud hammering noise and induces high stresses in the fitting and piping system. In the steam bubble collapse type of water hammering, cold or significantly subcooled condensate in a horizontal pipe or inclined pipe is put in motion by the differential pressure across the condensate. Due to the pitch of the pipe, steam flows over the sub-cooled condensate. The condensate rapidly condenses the steam and affects its velocity. The high velocity of the steam over the sub-cooled condensate creates waves in the surface of the condensate. A high enough wave will trap a steam bubble in the condensate. The suppressing of the steam bubble by the cold condensate causes a condensation-induced water hammer. The bubble collapse causes sharp pressure waves or water hammer. It should be appreciated that when water hammering occurs, undesired stresses to the piping system may result.
Unfortunately, in some circumstances the levels of condensate may collect in unexpected or unintended locations. When this occurs, the condensate may not be able to properly drain through a steam trap as desired. As a result, an unexpected water hammer event may occur.
Accordingly, while existing steam system arrangements are suitable for their intended purpose, there still remains a need for improvements particularly regarding the prediction of undesired conditions, such as condensate accumulation, and the identification of locations where the condensate is accumulating.